96 



to be considerably in defect. It would follow that the forest is deficient in tre«a of 

 Class II, and also it would appear of Class III, as the number is abont the same. 

 Class IV would, however, appear (a rough approximatiou only is possible) to be well 

 represented, and so would Class V. It may, therefore, be accepted that during (we 

 will assume) the next 60 years, until the crops of Class IV begin to be exploitable, 

 the fellings must be made with caution ; but that the crop will be thereafter fairly 

 complete if not altogether normal. This interval of 60 years Ts in fact a preparatory 

 period during which a provisional plan is required. 



As regards the sufiSciency or otherwise of the existing exploitable stock, we will 

 suppose the felling rotation adopted to be a very Ions one, say 30 years, and that the 

 whole area ia sub-divided into 30 portions each approximately equal in extent. Every 

 y^ar there would pass from Class II into Class I and become exploitable something 

 lessjhan 596 trees, or on one-thirtieth of the area ~- = 19 trees. Consequently 

 immediately before the commencement of the second felling rotation and ever after 

 the exploitable stock on the ground would be : — 



On the area felled over 30 years before, 30 X 19 trees. 



etc.. 



The total number of exploitable trees left standing would therefore be — 



19X (30+29 + . ..+2+l) = 8,835 trees. 



Therefore the surplus stock is 24,741—8,835=15,906 trees. 



As, however, the crop is defective in trees of Classes II and III, this surplus 

 ought, it the trees can be preserved in a healthy condition, to be utilised during the 

 whole of the preparatory period of 60 years. It would, therefore, be only permissible 

 to fell 15,906-7-60=265 trees of the surplus stock each year or, in all, 2654-596, 

 :=861 as a maximum each year. 



The foregoing discussion, as to the sufficienoy of the stock already exploitable, 

 proceeds en the assumption that the stock of trees in Class II is normal. But suppose 

 the maximum number of trees becoming exploitable each year, viz., 596, is below 

 the normal production which should annually be about one tree an acre or 1,200 treeii 

 in all. In this case it would be desirable to preserve on the ground a corresponding 

 stock which would be, with a felling rotation of 30 years, ^^|g2. [30-1-29+ ....1 } = 



-^^{30+1 }-^ =18,600. Here again it would only be permissible to fell 



(24,741 — 18,600)-T-60=102 trees of the surplus stock each year duriug the prepara- 

 tory period; so that the fellings would be reduced to 102+696=about 700 trees a 

 year. Again it might be that the exploitable stock is deficient. If there were only, 

 we will suppose, 4,741 instead of 24,741 exploitable trees, and the stock required 

 were, as in the last case, 18,600 trees, the forest would be very deficient in mature 

 stock. In the course of 60 years, the exploitable stock should be augmented by the 

 difEerencel8,600— 4,741=13,859 trees, or at the rate -^^^=231 trees a year. 



60 



In such a (vise, the number of trees in Class II remaining the same as before, there 

 ought not to be felled each year more than about 596 — 231=365 trees. 



{in) The French method. 



The method last described meets the diflSculty, so frequent 

 in India, involved in calculating the possibility of a mixed 

 crop containing only one or two saleable species, such as the 

 teak forests of Burmaj the deodar forests of the Himalaya, 



